pkg/41330: pre/post (de)install scripts don't have an SVR4 interface

[Lloyd Parkes <Lloyd.Parkes%ird.govt.nz@localhost>]

Hi all,
I would really appreciate it if someone could review this patch and commit it 
before the 2009Q2 feature freeze. It shouldn't affect any pkg_* users, but it 
will allow SVR4 pkg* users to get all the goodness that the (DE)INSTALL scripts 
provide these days.

Once I've seen what happens with @pkgdir, I'll also submit a patch for gensolpkg 
to take advantage of the pkg/41330 and actually deliver the pkgsrc install 
goodness to us poor suffering Solaris users.

Cheers,
Lloyd